Oral lesions are common in patients with AIDS and HIV infection. They are responsible for substantial morbidity and may represent the first clinical manifestation of HIV infection. Their appearance and clinical characteristics have been almost exclusively described in clinical series among homosexual and bisexual men with HIV infection, largely of middle class background. The demography of HIV infection is shifting towards persons who have used intravenous drugs and their sexual partners, largely of low socioeconomic status and minority background. There are few studies of oral disease in this central population in the AIDS epidemic. We propose to study the oral manifestations of HIV infection in a heterosexual, largely minority IVDU population in the Bronx, N.Y. The population will consist of 250 HIV seropositive men and women and 100 HIV seronegative controls in a methadone maintenance program, who are enrolled in an ongoing study of the natural history of HIV infection. Extensive behavioral, clinical and laboratory data are available for this population. The study will provide a systematic population-based comparison of the prevalance and incidence of oral, periodontal and dental lesions in HIV seropositive and negative individuals. The study will also provide information on the response to treatment of oral and dental conditions and investigate possible differences between HIV seronegatives and seroposi ves.